Foundation inspection: home inspector, engineer or contractor?

Three kinds of foundation inspection

People use "foundation inspection" for three very different visits. Know which one you are paying for.

Who	What they do	What you get	Typical cost
Home inspector	A visual walk-through, usually for a sale. In Texas, the inspector must give a written opinion on foundation performance and report visible signs such as binding doors, sloping floors and cracks[2].	A section of the home inspection report	$250 to $400 for the whole home inspection[3]
Structural engineer	Measures floor elevations, studies the cause and decides whether repair is advisable[1].	A signed report and, if needed, a repair design	$300 to $750 for a foundation inspection[3]; $500 to $3,000 for a report that sets the repair method[4]
Repair contractor	A free or low-cost visit by an estimator.	A sales proposal for that company's repair	Often free

FPA defines a structural engineer as a licensed professional engineer who evaluates a foundation "to determine the performance of the Foundation and the advisability of Foundation repair"^[1]. That last part is the point: the engineer's job includes telling you when repair is not needed.

FPA's three levels of investigation

The Foundation Performance Association, a Houston engineering group, uses three levels taken from the ASCE Texas Section guidelines^[1].

• Level A: first impressions. An interview about the home's history, a walk-through, and notes on what affects the foundation. FPA says this level is normally used in real estate inspections^[1].
• Level B: measured. Everything in Level A plus a review of past reports and repair papers, floor elevations on a scaled drawing, contour lines, and tilt and deflection calculations. It also maps trees and poor drainage^[1]. FPA says its performance limits can only be applied with a Level B or C investigation^[1].
• Level C: forensic. Adds testing the engineer thinks is needed, such as soil sampling, a hydrostatic leak test, concrete coring, groundwater monitoring and aerial photo review. FPA says it is used when a more exact cause is needed, such as in legal disputes^[1].

For a house you think is moving, ask for at least Level B. A report with no elevation numbers is an opinion, not a measurement.

What a good engineer's report contains

• An elevation plan. FPA says floor levels should be measured with a device that reads to 1/8 inch or better, with accuracy of plus or minus 1/16 inch or less. A carpenter's level is "not sufficient" for an elevation plan^[1]. The report should name the equipment used^[1].
• A reference point, usually near the center of the house, marked on the plan so the next survey can repeat it^[1].
• Tilt and deflection numbers. FPA's recommended limits are tilt of 1% or less across the whole slab and deflection of L/360 or less. FPA adds that these criteria "are not intended to supersede engineering judgment"^[1].
• Site factors: large trees, drainage, gutters and past repairs^[1].
• A cause and a recommendation: repair, monitor, fix drainage, or do nothing.
• If repair is advised: a pier layout with number, type and location.

One survey cannot prove movement

New slabs are not perfectly flat. FPA notes that new foundations are rarely level and often move during construction, and its committee found most residential slabs are built within 1.0 inch of level^[1]. So a first survey only shows how out of level the floor is today. It cannot show how much moved, or when.

That is why FPA recommends that home buyers get a baseline elevation survey^[1]. A second survey later, compared point by point, shows real movement. Keep every survey you pay for.

Symptoms that are often not the foundation

FPA publishes a list of problems commonly blamed on the foundation that have other causes^[8]:

• Nail pops and drywall cracks from wood framing shrinking. FPA suggests waiting about two years for shrinkage to settle, then repairing^[8].
• Doors that bind because a hinge is loose or too small^[8].
• Cracks in single floor tiles that do not line up with cracks in nearby tiles^[8].
• Brick cracks at window lintels from rusting steel^[8].

NAHB guidance agrees that cracks alone are not necessarily a structural concern. They matter more when they come with doors and windows that will not work or with steep floor slopes^[9].

Permits that require an engineer

Some cities make the engineer part of the repair, not an option.

• Houston: a foundation repair permit for a slab-on-grade house needs plans from a Texas-licensed engineer showing the location, quantity and type of piers^[5].
• San Antonio: repairs must be designed by, or done under the guidance of, a Texas professional engineer, and inspections clear only on the engineer's inspection letter^[6].

Rules differ by city. See foundation repair permits by city.

How to hire the engineer

• Check the license. In Texas, the Texas Board of Professional Engineers and Land Surveyors has a public "find an engineer" roster^[7]. Other states have their own boards.
• Hire someone with no stake in the repair. Ask whether they get any payment from repair companies.
• Ask what level of investigation the quote covers, and whether a plumbing test is advised.
• Ask about a follow-up visit after repair and a final letter. San Antonio requires one for the permit^[6].

When to call a pro

• Doors and windows start sticking at the same time new cracks appear: hire a structural engineer.
• You are buying a slab house in clay country: ask for a baseline elevation survey.
• A repair company has quoted piers: have an independent engineer review the layout before you sign.
• Your city requires an engineer for the permit: hire one before choosing a contractor.